1. Field of the Invention
This invention relates to a unique method and system for sensing position of an occupant within a vehicle where laser and sensor assemblies continuously monitor occupant position in three different zones.
2. Related Art
Many vehicles have airbag systems that are used to restrain occupants within a vehicle under certain deceleration requirements. If the vehicle decelerates suddenly, such as when a collision occurs, occupants will tend to continue to move forward due to inertial effects. An airbag is deployed under these circumstances to decelerate the occupants"" impact speed before they contact a vehicle structure, such as a steering wheel or dashboard. The deployment of the airbag decreases the likelihood of serious injury for the occupants.
If vehicle occupants are positioned too close to the airbag, it may be desirable to decrease the deployment force of the airbag or to prohibit deployment of the airbag to prevent injury to the passenger from the impact of the airbag. Occupant sensing systems are used to provide information to optimize or suppress deployment of an airbag if an occupant is determined to be too close to the airbag. Some systems use sensors to determine when a seat belt has been withdrawn from the retraction reel beyond normal operative requirements. Other systems use optical or acoustic signals that are transmitted laterally across the vehicle extending parallel to the dashboard to determine proximity of an occupant to the dashboard. Other systems use transmitting/receiving sensors directed toward a vehicle dash to determine when an occupant is adjacent to or touching the dash.
These systems are complex and expensive. Often these complicated systems are difficult and time consuming to install and provide inaccurate position measurements. Thus, it is desirable to provide a simplified method and system for sensing position of an occupant within a vehicle that is easily installed and maintained. The simplified system should be compact and provide continuous and accurate readings for occupant position that are used to optimize or suppress deployment of an airbag if an occupant is determined to be too close to the airbag.
In a disclosed embodiment of this invention, a vehicle occupant sensing system includes a laser array and three sensor assemblies. The laser array is mounted to a vehicle structure and generates a first beam directed toward a first occupant zone, a second beam directed toward a second occupant zone, and a third beam directed toward a third occupant zone. The first sensor assembly receives reflection beams resulting from the first beam striking a first portion of an occupant located in the first zone. The first sensor assembly generates a first signal proportionally representing the amount of the occupant present in the first zone. The second sensor assembly receives reflection beams resulting from the second beam striking a second portion of the occupant located in the second zone. The second sensor assembly generates a second signal proportionally representing the amount of the occupant present in the second zone. The third sensor assembly for receives reflection beams resulting from the third beam hitting a third portion of the occupant located in the third zone. The third sensor assembly generates a third signal proportionally representing the amount of the occupant present in the third zone. A central processor is used to receive and combine the first, second, and third signals to determine the position of the occupant within the vehicle.
In a preferred embodiment, the laser array and sensor assemblies are all enclosed within a common housing that is mounted to a vehicle structure. A lens is installed within the housing to control the size, shape, and direction of the laser beams. Preferably, the first zone is defined as an area normally occupied by an upper portion of the occupant, the second zone is defined as an area normally occupied by a middle portion of the occupant, and the third zone is defined as an area normally occupied by a lower portion of the occupant. The lens directs the first beam to the first zone, the second beam to the second zone, and the third beam to the third zone.
In a further preferred embodiment, each beam forms a light curtain that is at least forty degrees wide and at least three degrees thick, with each beam being spaced apart from one another by at least ten degrees. Position of the occupant is continuously monitored as the sensor assemblies receive reflections resulting from the light curtains striking an occupant seated within the vehicle.
A method for sensing an occupant position within a vehicle includes the steps of generating a first laser beam toward a first zone, receiving a reflection from the first laser beam when the first laser beam strikes a portion of an occupant in the first zone, and generating a first signal representing a first proportional amount of the occupant in the first zone. Further steps include generating a second laser beam toward a second zone, receiving a reflection from the second laser beam when the second laser beam strikes a portion of an occupant in the second zone, and generating a second signal representing a second proportional amount of the occupant in the second zone. Additional steps include generating a third laser beam toward a third zone, receiving a reflection from the third laser beam when the third laser beam strikes a portion of an occupant in the third zone, and generating a third signal representing a third proportional amount of the occupant in the third zone. The first, second, and third signals are combine to determine occupant position within the vehicle. The first, second, and third signals can be used to generate a control signal for controlling the deployment of an airbag based on occupant position within the vehicle.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.